JSemaphore.cpp

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/***************************** License **********************************

 Copyright (C) 2008 by Communicative Machines
 http://www.cmlabs.com   All rights reserved.

 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

************************************************************************/
// JThread.cpp: implementation of the JThread class.
//
//////////////////////////////////////////////////////////////////////

#include "JSemaphore.h"

#ifdef WIN32
        #include "win32/JSemaphore_Win32.cpp"
#else
        #include "linux/JSemaphore_Linux.cpp"
#endif



namespace cmlabs {

// *****************************************************************
// Unit Testing
// *****************************************************************


bool JSemaphore::unitTest() {
        JThread* thr = new JThread();
        bool res = thr->unitTest();
        delete(thr);
        return res;
}









// *****************************************************************
// WriteAccessMutex
// *****************************************************************

WriteAccessMutex::WriteAccessMutex() {
        currentReadCount = 0;
}

WriteAccessMutex::~WriteAccessMutex() {
        accessMutex.LeaveMutex();
}

bool WriteAccessMutex::gainReadAccess(long timeout) {
        if (!accessMutex.EnterMutex(timeout))
                return false;
        currentReadCount++;
        accessMutex.LeaveMutex();
        return true;
}

bool WriteAccessMutex::releaseReadAccess() {
//      accessMutex.EnterMutex(100);
        currentReadCount--;
        if (currentReadCount < 0)
                currentReadCount = 0;
//      accessMutex.LeaveMutex();
        return true;
}

bool WriteAccessMutex::gainWriteAccess(long timeout) {
        
        JTime start;
//      JTime now;
//      long ms;
        
        if (!accessMutex.EnterMutex(timeout))
                return false;

        while (currentReadCount > 0) {
        //      accessMutex.LeaveMutex();
                wait(10);
                if (JTime() - start > timeout) {
                        printf("### Timed out waiting for write access... ###\n");
                        accessMutex.LeaveMutex();
                        return false;
                }
        //      now = JTime();
        //      ms = timeout - (now-start);
        //      if (ms < 0) {
        //              printf("### Timed out waiting for write access... ###\n");
        //              return false;
        //      }
        //      if (!accessMutex.EnterMutex(ms))
        //              return false;
        }

        return true;
}

bool WriteAccessMutex::releaseWriteAccess() {
        accessMutex.LeaveMutex();
        return true;
}
















} // namespace cmlabs

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